Method of steam distillation



May 26, 1953- R. w. HEATH 2,640,018

METHOD OF STEAM DISTILLATION Filed July 25, 1949 3 Sheets-Sheet 1 SEPARATOR CONDENSER rCOMPRESSOR INVENTOR.

RONALD W Hear/I Ar ram/5y.

y 5, 1953 R. w. HEATH 2,640,018

METHOD OF STEAM DISTILLATION Filed July 25, 1949 3 Sheets-Sheet 2 STEAM GENERATOR 'gSTILL IN VEN TOR.

12 RON/v.0 H FITH A -r TORNE y.

May 26, 1953 R. w. HEATH 2,640,013

METHOD OF STEAM DISTILLATION Filed July 25, 1949 s Sheets-Sheet 5 COMPRESSOR 175 1 A VAPORATOR I ,5 SEPARATOR COMPRESSOR INVENTOR. Ro/wuo HEATH ATTORNEY.

Patented May 26, 1953 METHOD OF STEAM DISTILLATION Ronald W. Heath, Long Beach, Calif., assignor to Signal Oil and Gas Company, Los Angeles, Calif., a corporation of Delaware Application July 25, 1949, Serial N 0. 106,622

18 Claims.

This invention may be summarized as follows: It relates to a process of steam distillation in which steam is commingled with a material to be distilled with said Steam at a pressure, at or lower than the saturation pressure of the steam at the temperature of distillation, to produce a vapor composed of steam and vapor from the material undergoing distillation. The mixed vapors are compressed and thus heated by the work done in the compression. The superheat and the latent heat of condensation of the compressed vapors are removed to produce a water condensate at the said higher pressure. The water condensate is then passed into a zone of lower pressure, but at a pressure as high or higher than the distillation zone but less than the pressure of the condensation zone and the water is vaporized and the steam employed for said steam distillation. In a modification of the invention the latent heat of vaporization of the steam may be in part supplied by the heat in the compressed vapors passing to the steam condensation stage, previously referred to. There is thus a transference of the latent heat of condensation of steam at high pressure to supply the latent heat of vaporization of the steam at lower pressure. In addition, because the water undergoing vaporization, as steam is vaporized at a temperature lower than the temperature of the water at which the water condenses from the compressed vapors, the water undergoing vaporization to make steam may be circulated as coolin medium in the condensation step, and the water thus heated may be recirculated to the steam forming stage. In addition the heat of the compressed vapors may also be transferred to the incoming material to be distilled by heat exchange between this feed and the high temperature vapor or liquid streams. Thus, the heat of compression of the vapors is employed as the course of heat for the vaporization steps and by maintaining proper pressure levels, the unvaporized liquid residue from the vaporization step may act as condensation or absorption medium for vapors or gases which are at a higher temperature than the residue.

In addition to the efficiencies attained by this procedure, and in addition to the simplification of apparatus obtained by employing this cycle, I also obtain an economy in cooling water and fuel and in water for generation of process steam, and avoid the construction and operation of separate process steam equipment. The water is employed in cycles of operation and the water requirement is reduced to a minimum. Thisis particularly important in desert or waste areas such as are found in many oil fields throughout the world. In refineries or natural gas plants where steam distillation is required or may be economically employed, the problem of water supply is a primary consideration. In such areas the economy of water utilization obtained by my system and process is an important consideration in making such process possible in such localities.

These and other objects of my invention will be clear to those skilled in this art from the following description taken together with the drawings, in which Fig. 1 is a flow sheet of one form of the process of my invention; 7

Fig. 2 is a flow sheet of another form of the process of my invention;

Fig. 3 is a flow sheet of another form of the process of my invention;

Fig. 4 is a flow sheet of another form of the process of my invention; and

Fig. 5 is a flow sheet. of another form of the process of my invention.

Referring to Fig. 1, the material to be distilled is passed through the line I, heat exchange coil 2 (or by-passed in part or whole by control of valves la and lb) through heat exchange coil |3b and heater 2a into the still 3 where a portion is vaporized and the unvaporized material Withdrawn through line l3 by controller valve I4 and through the heat exchange coil 13a in heat exchange with coil [32). The vapors exit through 4 and are compressed by compressor 5 and passed through heat exchange coil 6' in heat exchange with coil 6 and through heat exchange coil 2' in heat exchange with coil 2, and then into the separator-condenser I. Condensate is collected in l and the water withdrawn through line H and the remaining condensate, if lighter than water, withdrawn through 9 under the control of valve ID. The water. passes under its own pressure through line I I through pressure reduction valve I? with any water desired to be added through I la, heat exchange coil 6 in exchange with compressed gas in 6', into the chamber 3. The uncondensed material in l is withdrawn through line l5 under the control of valve NS for other operations or disposal, and the unvaporized material in 3 is withdrawn through line l3 under the control of valve M.

It will be observed that in order for the water enterin by valve l2 to vaporize in 3,'the pressure in still 3 must be not above at the vapor pressure of the water at the temperature attained in 3. Exchange of heat in 6 and 6 may be and probably will always be sufficient to vaporize all of the water passing through valve l2. The compressor 5 will compress the vapors to a high pressure in 6 and the temperature will rise as the result or" the heat of compression. Due to the increase in pressure, the temperature at which the vapors will condense is increased. If the drop in temperature as a result of imparting the latent heat of distillation to the liquid passing via [2 is insufficient to drop the temperature to the desired temperature in l, the compressed vapors must be cooled. This may be attained by heat exchange with the circulating water in I l in heat exchange coils '5 and ii, and if necessary by heat exchange with the incoming material by a proper setting of valves la and lb in the by-pass line. If this is not enough cooling, extraneous air or water cooling may be resorted to. The heat exchange in 6 and 6' provides nearly all and usually all of the latent heat or vaporization of the water entering into 3. Because of the heat content of the non-steam vapors, the heat available in the compressed vapors may be more than enough to vaporize the water. If needed, additional heat may be added to the feed by exchanger I32) and heater 2a.

The following examples may be given as an illustration of the principles of the operation of my processes and not as a limitation thereof, and, as will be understood by those skilled in this art, the illustrated applications of this principle, shown as applied to distillation of a petroleum oil, is equally applicable to any distillation process in which a phase separation between the water condensate and the remaining distillate may be effected.

Example 1 In Fig. 1 the feed may be a hydrocarbon gas oil or fuel oil fraction containing 8.6 mol per cent of hydrocarbons in the gasoline range. Still 2 is operated at a pressure of 10 pounds gage and a temperature of 260 F. The steam rate in. still 3 is about 1.4 mole of steam per mol of such lighter hydrocarbon material. The condenser separator i is operated at a pressure of 30 pounds gage and a temperature of 260 F. The 260' F. vapor passing through 4 is compressed by pump 5 to 30 pounds gage plus, i. e., to a pressure suificiently above the pressure in l to permit flow through the lines between the compressor and the separator. For all practical purposes this pressure drop may be ignored. The heat of compression will raise the temperature to about 350 F. In passing through the heat exchange coils B, it is cooled to 280 F. and cooled down to about 260 F. in the exchanger 2'. At this temperature and pressure (giving effect to the partial pressure of the gasoline hydrocarbons), the gasoline hydrocarbons will condense and the residual water vapor will also condense. The condensation temperature of the water vapor at 30 pounds gage 274 IR, and at 260 F. substantially all of the water vapor will condense, as will the hydrocarbons of this example, leaving some uncondensed fixed gases and vapors passing through l5.

The water separates from the condensed hydro carbons and is withdrawn under its own pressure i Example 2 The same principle applies when steam. distill- 4 ing in vacuum, but higher compression ratios are obtainable on the compressed vapors.

The still 3 is operated at a pressure of 3 pounds per square inch absolute (p. s. i. a.) and at a temperature of F., using the same feed and steam rate as in the previous example. The vapors are compressed to produce a pressure of about 14.? p. s. i. a. in l, i. e., atmospheric pressure, and raised to a temperature of about 400 F. In passing through heat exchanger 6 the vapors are reduced in temperature to about F. and then cooled in exchanger 2 to a temperature of about 100 F., and condensate is separated in l. The water separated at 100 F. is passed through valve l2, reduced in pressure to a pressure of 3 p. s. i. a, and passed through heat exchanger 6 wherein it is vaporized and superheated to a temperature of 300 F.

It will be observed that in both of the above examples the water travels in a closed cycle and therefore, assuming a constant flow rate of oil entering 3, the circulation of the water to keep a constant level in 1 will thus control the volume of steam at the partial pressure of steam in 3. The only loss of water will be that lost in the vapor exiting through [5 or lost by entrainment in 13 or 9. These losses will be insignificant. It will also be observed that all heat exchange operations are at relatively high temperatures and that none of the vapor or liquid streams require cooling water at atmospheric temperature. Thus, the water requirements are reduced to a minimum.

In the cycle illustrated in Fig. 2, the tempera ture of condensation of the steam is higher than the temperature of the distillation, and water is circulated from the still to act as a condensing medium. The material to be distilled enters through 11, passes through valve l0 and the heat exchange coil 19 in exchange with coil 3?, with additional material passing through the valved by-pass line 2B, through heat exchange coil 25a in heat exchange with coil 26 and the combined streams then pass through the heater 2! into the evaporator 22. The vapors pass through 23 and through compressor 24 pumped through exchange coils 25 and 26 into the distillate collector 21, and the uncondensed vapors removed from 28 for further processing. Any condensate lighter than water is removed from 3|] and the Water is withdrawn through line 3|, passed through heat exchange coil 32 by the pressure reduction control valve 33, into the evaporator 22. Residue lighter than water is withdrawn through 33 and Water is withdrawn through line 34 by valve 35 and pumped by pump 36 and heat exchange coil 37, line 38, into the line 29. Any additional water, if desired, may be passed through line fill under control of valve 4!.

In this cycle the vapors generated in low pressure still 22 are compressed and heated by heat of compression by pump 24 and passed through coil 25 into the condensate receiver 21. The heated compressed vapors are cooled and the latent heat of condensation of the water and distillate vapors are withdrawn in exchangers 32 and 26a.

The water circulating from the evaporator 22 by way of pump 36 is at a lower temperature than the operating temperature in 21' and thus acts as a cooling and condensing medium 21. Additionally, it may be cooled by heat exchange with the incoming material to be distilled. The circulating water thus acts to further condense steam and condensate in 21. The water thus 580 into the tower i.

with water entering through 58 and the unconevaporated and the remaining water is removed through 34. The control of the amount of water evaporated, and therefore the partial pressure of the steam in 22, is by the rate of recirculation of the water through the valve 33, and by control of the temperature of the material passing through 2| into 22.

Fig. 3 shows a similar cycle in which the hot water from the condenser-separator is passed to an evaporator-cooler and steam still for generation of the steam and the cooling of the water, instead of directly into the main still where these functions are combined with the distillation of the incoming feed material.

In the cycle illustrated in Fig, 3, the steam generation step is in a unit separate from the still but operating at substantially the pressure of the still, i. e., at some higher pressure than the still, determined by the back pressure of the vapor lines connecting the two units. Thus, material to be distilled may be introduced through line 42 and a portion or all of the stream may be passed via valve 42a and heater 42: into the evaporator 44 where it meets steam entering through 45. The unvaporized material is withdrawn through line 45 under the control of valve 41. The vapors including steam are withdrawn through line 48 by compressor 45 and may be passed either by means of valve 55 directly into receiver 55 and/or by-passed through line 52 by means of valve 5| and passed through the heat exchange coil 53 or by means of valve 55:]. and heat exchange coil 55?) in exchange with a portion of the incoming feed material icy-passed through valve 550 and heat exchange coil 55d back into line 55.

higher boiling than water (if there be any such 1 present) it may be withdrawn through the valved line 55a and returned to the still. The vapors then pass through the compressor 55b and line The vapors are washed densed vapors are withdrawn through 59. The condensate lighter than water is withdrawn through 55 and by control of valve fiiib returned to line 42 and the hot water is withdrawn through '6! under control of valve 52 and'pased into the evaporator 54.

Steam is withdrawn from the evaporator through 5201 and cooled water is withdrawn through line 53 by means of pump 65 passed to the line 65 and then to line 55. The steam passes through knock-back 55 wherein 'a portion may be recondensed by exchange with a portion of the incoming feed by-passed via valve 65, line 5?, heat exchange coil 58 back to line 42. The steam condensate collecting in 55 returns to 54 by gravity and the uncondensed steam passes via line 45 and valve itle into still Returning to the uncondensed distillate vapors in 59, it is passed through heat exchange coil 69 in heat exchange with a portion of the feed from 42 by-passed through valve 10 and heat exchange coil H. The cooled vapors pass into separator 12, wherein the water is" separated and withdrawn via line 13 and valve 14 and returned to 54. The condensate, if lighter than water, is withdrawn via line I! and valve I8 and the uncondensed vapors are withdrawn via line 15 and valve 16.

It will be observed that the evaporator 54 is at the pressure of the still 44 or somewhat higher, depending upon the back pressure in line 45, knock-back 65, and the connecting lines. The material passing through 48 is heated by the heat of compression by means of compressor 49 and has its temperature raised above that in 44 or 54. The material in passing through 53 is condensed at pressures in excess of the Pressures and temperatures maintained in 54. The latent heat of condensation at this higher pressure is transferred to supply the latent heat of vaporization of the water at the lower pressure in 54. The temperature of the condensate in 51, due to the higher pressures in 51 than obtains in 54, will be higher than the temperature of the hot water in 54 and this hot water may then circulate through line 63 to aid in the condensation of steam and other vapors in 51. The Water then exiting from 51 via 6| is at a higher temperature than the equilibrium temperature of the water in 54 and when it enters 54 will vaporize. Only a fraction of this Water is vaporized, the fraction depending upon the temperature of the water passing through BI and the heat imparted by coils 53 and temperature and pressures maintained. This then controls also the volume of steam entering through 45. Because this vaporization rate may be excessive for the steam rate required in 44 some of the steam is condensed in 65 and the resultant condensation of the steam holds and controls the steam rate in 44.

Example 3 The following example, which relates to the flow sheet of Fig. 3, will also be pertinent in illustrating the fundamental relationships of the flow sheet of Fig. 2. For purposes of illustration, as explained in connection with Examples 1 and 2, I will use the same feed material and the same steam rate as in Examples 1 and 2.

In Fig. 3, the still 44 is maintained at a temperature of F. and a pressure of 3 p. s. i. a. The inlet temperature of the feed into 44 is F. Assume for purposes of illustration the material entering line 42 passes through coil H and coil 68, valves 55c and 42a are closed. The evaporator 54 and knock-back 55 are maintained at about 6 p. s. i. a. by the proper setting of valve 45a. The vapors are compressed in compressor '49 to a pressure sufiicient to maintain. a pressure of 15 p. s. i. a. in 56 and are heated to a tem perature of about 400 F. by compression. In passing through the coil 53, valves 50 and 50a, being closed, the vapors are reduced in temperature to about F. Normally no water would condense due to the partial pressure of the hydrocarbons present, but if there be any high boiling oil fractions, they may be condensed and returned to the still. The vapors withdrawn from 56 are further compressed in a second stage of compression by means of compressor 56b to a pressure sulficient to maintain 60 pounds gage in 51 and the vapors are heated by compression to a temperature of about 435 F. and introduced into the separator 51. Relatively cool water withdrawn from evaporator-cooler 54 at a temperature of about 170 F. is passed by pump 64 into 51 and by heat exchange with the hot vapors is heated to a temperature of about 200 F., cooling the vapors to approximately this temperature.

The hot water is then passed into the evaporator-cooler steam still 54. At the circulation rate of the water passing to the separator 51, because of the temperature of the water and the heat in the vapors passing through the coil 53, an excessive vaporization of the water in 54 results which is in excess of the steam rate desired in 44. This has the effect of cooling the water in 54 to the desired low temperature. The fraction in excess of the desired steam rate is condensed in 65 by exchange with the oil passing through 68 and the condensation of the steam fraction in 65 controls the volume of steam passed to stil1 44, and therefore the steam rate. At the steam rates indicated, about /3 of the steam generated in 54 is condensed in 65.

The vapors exiting through 59 are cooled by exchange with the incoming feed. to reduce them to a temperature of about 85 F. and the preheated oil passing through the coil 58 is heated to a temperature of 155 F., the initial temperature of the feed being adjusted to obtain the desired temperature of 155 F. The heater 43 is then not used, or if it is to be used, the initial temperature of the feed may be lower.

The water condensate is withdrawn via line I3 and valve I4 and returned to 54. The hydrooarbons are withdrawn via line I? and valve I8 and the uncondensed gas withdrawn via line I3 and valve I6.

In the previous examples as illustrated by Figs. 1. 2 and 3, the latent heat of evaporation of the steam Was supplied in part by indirect heat transfer from the heat of the compressed vapors. Where the pressures and temperatures are favorable, the steam generation may be made by flash evaporation. The heat necessary to generate the steam vapors is obtained by compressing the steam vapors and washing the compressed steam with the water cooled by the evaporation in gencrating the steam. This is illustrated by flow sheet of Fig. 4.

The incoming material to be distilled passes through line I8 and heat exchange coil lilo. in exchange with coil I21) via valve 780 and heat exchange coil 82 (in exchange with coil H6) and line 81, or by-passed in whole or in part via valve 78?) into line 88 and may be apportioned by setting of valves I3 and 80, part to be pa. sed through coil 32 and line 81 and part through line 83, coil 84, and line 88 and combined with line 88 and introduced into the still 89.

The vapors from 89 pass via line 93 and are compressed by compressor 94 and the compressed and heated vapors enter the fractionating tower $6 in which they are separated into fractions by aid of the recirculated relatively cool water added through 91. Condensate, if of lower specific gravity than water, is separated via line IM and valve I82 and introduced into line 92 whereby it is introduced as a reflux in still 85!. The relatively hot water is passed through line 98 and valve 99 into line IOII from which it passes into the steam generator 85. Steam vapors separated from the water in 85 are in part condensed by the heat exchange coil 84 and the uncondensed fraction passes via valve 9! and line 90 to enter the steam still 89.

The unevaporated relatively cool water is withdrawn from 85 via line I01 and pumped by pump I 08 into lines 91 and I06 by proper control of valves I09 and I III. The uncondensed fraction of water and distillate vapors are withdrawn from via line I03 and compressed to a higher pressure by compressor I04 and introduced into rectification tower I05 in which separation of fractions occurs by aid of the relatively cool water introduced via I116.

The uncondensed fractions pass via line II 5 and coil III; in heat exchange with coil 82 and are introduced into the separator I I 1. The water condensate in IE5 is withdrawn via line H3 and valve H4 and introduced into line I90. The con densed distillate fraction, if lighter than water. is withdrawn via line III and valve H2 and passes into line 92.

In the separator I I1, the lightest fraction, if lighter than water, is withdrawn via line I22 and valve I23 and passed to storage or other disposal. The water condensate is withdrawn via line HI and valve I20 and passed into line I00. The uncondensed vapors and gases are withdrawn via linc II 8 and valve H8. The residue withdrawn. from still 89 via line I24 and valve I25 and pump I25 is passed through coil I27 in heat exchange with incoming material via line I8.

To illustrate the operation of this cycle and for purposes of comparison with the other cycles, the steam distillation of the material employed to illustrate the operation of the cycles of Figs. 13 inclusive, may be employed, employing also the same steam rate.

Example 4 The oil entering via line 88 may be at a temperature of F., the still being operated at a temperature of 145 F. at 3 p. i. a. in the presence of steam introduced via 90. The residue is withdrawn at a temperature of 145 F. and may, if desired, be used to preheat part of the feed which is introduced at the desired initial temperature.

The vapors via 93 are compressed from 3 p. s. i. a. to 15 p. s. i. a. in 96 and are thus heated to a temperature of about 400 F. They are reduced in temperature to about 185 F. by heat exchange in 96 (at 15 p. s. i. a.) with water circulated from 85 at a temperature of about F. The water condensate is withdrawn from 96 and introduced into the evaporator cooler 85 in which it is reduced in temperature to about 170 by evaporation in 85 at a pressure of 6 p. s. 1. a.

The uncondensed vapors from 56 are further compressed to obtain a pressure of 60 pounds per square inch gage (p. s. i. g.) in I05 and are thus superheated to a temperature of about 435 F. and are introduced into rectifying tower I05 at about this pressure in which they meet a stream of water at about 170 F. circulating from 85.

The condensed water is withdrawn via line H3 and valve II 4 and recirculated to the flash evaporator 85. The oil condensates in 9G and I05 are withdrawn via lines IUI and H2, respectively, and recirculated as reflux to the still 89 via line 92.

The vapors and gases passing at about 200 F. via line II 5 are reduced in temperature in ex changer I I6 to a temperature of 85 F. and separated in separator I I "I at substantially 60 p. s. i. g. The water condensate is withdrawn via line I20 and valve [H and introduced into line I00.

Returning to the flash evaporator 85, the heat in the stream entering 85 is such that at the pressure in 85 the amount of water vaporized is in excess of the steam rate desired. The excess is separated by .condensing the undesired fraction, 1. e., about 36% of the generated steam. The latent heat of condensation thus withdrawn is used to add heat to the feed passing to the still 89. Thus the steam rate is controlled with out raising the pressure or temperature in still I35.

In the previous flow sheets 2, 3, and I, the water circulated was in excess of the water needed for steam generation for use in the steam still. In Fig. is illustrated a system in which the water circulated is equal to the steam require ment. The feed passes through line I28 and by control of the valves I29 and I30 may-be passed in whole or in part through heat exchange coil I3I and line I32 and then by control of the valves I33 and I34 may be passed in whole or in part through heat exchange coils I35 and if necessary through the heating coil I3I by proper control of valves I38 and I33 into still 140. I

The vapors from still I40 pass via line MI and compressor I42 and by control of valves I43 and I44 and I43 may pass via heat exchange coil I45 in heat exchange with coil I3! and through coil I46 in evaporator I41 and through cooling coil I48 into the rectifying tower I49 or directly (valve I43 and I43 being opened and I44 closed) through cooler I48 into still I49. The water condensate passes out of the tower via line I50 under control of valve I5I to be introduced via line I52 into the water evaporator I41. The condensate, if lighter than water, passes via line I53 controlled by valve I54 to be introduced as a reflux in still I40.

The overhead vapors from I49 pass via line I54 and are compressed by compressor I55 and may pass in whole or in part through coils I56 in evaporator I41, by control of valves I51 and IE8, and then in part or in whole through coil I59 in heat exchange with coils I35 by proper control of valves I6I and IE0. The vapors are then introduced into the separator I62. The uncondensed gases are withdrawn via I63 by control of ValVeIIS I. The water condensate, if any, is withdrawn via line I65 and valve I66 to pass with any make-up water as desired introduced via line I61 and valve I68 to pass into line I52.-

Condensate lighter than water is withdrawn via line I69 and by control of valves I10 and III may be passed in part to storage via I12 and in part via I73 to be introduced as reflux into rectifier I49.

The operation or this cycle may be illustrated and compared with the other cycles by employing the ieedmaterial and steam rate of the other examples. I

Erample 5 The still I40 is operated at a temperature of about 145 F. and a'pressure of 3 p. s. i. a. The vapors are compressed in I42 to a pressure sufficient toobtain 15 p, s. i. a. in I49 and heated to a temperature of about 400 F. The vapors from the compressor I55 are compressed from a temperature of about l F. and pressure of 15 p. slifaito a pressure of 6-0 p. s. i. g. in I62. The gase'sare heated by this compression to a temperature of 435 F; The available heat in the hot gases will be, in the case of the example given, in excess of that necessary to generate thesteam. In fact, only a portion of the heat is necessary for this purpose. The remaining heat may be dissipated'by heat exchange with the incoming red. The coils may thus be by-passed in part 10' or whole to limit the heat required to vaporize all the water entering via I52 to maintain an initial constant level of water in I41.

While I have for purposes of illustration .referred the application of my system. to the distillation of petroleum oil containing hydrocarbons in the gasoline range, my invention is not so limited and may be employed for the steam distillation of any liquids or solids where the vaporization temperature and pressure of the still are such that at such pressure and temperature steam may be generated from liquid. Numerous examples will suggestthemselves to those skilled in this art as a result of the teachings of this application.

While I have described a particular embodiment of my invention for the purpose of illustration, it should be understood that various modifications and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims. i

I claim:

1. A method for steam distillation, which comprises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature, removing the vapors containing steam from the undistilled residue, compressing, the mixed vapors above the pressure at which distillation occurred, heating said mixed vapors by such compression above the temperature of distillation, cooling said mixed vapors to condense water from said vapors at said higher pressure, reducing the pressure on said water to substan. tially the pressure of said distillation and passing. said water in heat exchange with the compressed vapor thus cooling said vapors, vaporizing a portion or said water at said lower pressure to form steam, leaving some water unvaporized, introducing said steam into said distillation zone, passing said unvaporized water in direct contact with said compressed vapors at a higher pressure than said lower steam forming pressure, and cooling said compressed vapors by heat exchange between said vapors and said water by said direct contact at said higher pressure.

2. A method for steam distillation, which comprises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature, removing vapors containing steam from the undistilled residue, compressing said mixed vapors above the pressure at which said distillation occurred, heating said mixed vapors by such compression above the temperature of distillation, cooling said mixed vapors by indirect heat exchange with a water maintained in a vaporizing zone at a pressure substantially that of .said distillation zone, vaporizing said water to form steam, introducing said steam into said distillation zone, condensing water from said cooled vapors at a pressure and temperature substan tially higher than is maintained in said water vaporizing zone, separating said condensed water, reducing the pressure onsaid Water, introducing said water into said water vaporizing zone at said reduced pressure, removing water from said water vaporizing zone, introducing said removed water into contact with the compressed vapors at a pressure substantially higher than said water vaporizing zone, and condensing said compressed vapors at said higher pressure.

3. A method for steam distillation, which comprises passing steam into a. material undergoing distillation in a distillation zone at a distillation temperature, removing vapor containing steam from the undistilled residue, compressing said mixed vapors above the pressure at which distiller;- tion occurred, heating said mixed vapors by such compression above the temperature of distillation, cooling said mixed vapors by indirect heat exchange with a Water maintained in a vaporizing zone at a pressure substantially that of said distillation zone, vaporizin said water to form steam, partially condensing said steam, separating the uncondensed steam from the steam condensate, introducing the uncondensed steam vapors into said distillation zone, commingling the steam condensate with the water in said Water vaporizing zone, condensing water from said cooled vapors at a pressure substantially higher than is maintained in said water vaporizing zone, separating said condensed water, reducing the pressure on said water, and introducing said waterinto said water vaporizing zone.

4. A method for steam distillation which comprises passing steam into a material un-. dergoing distillation in a distillation zone at a distillation temperature, removing vapors containing steam from the undistilled residue, compressing said mixed vapors above the pressure at which distillation occurred, heating said mixed vapors by such compression above the temperature of distillation, cooling said mixed vapors by indirect heat exchange with a water maintained in a vaporizing zone at a pressure. substantially that of said distillation zone, and vae porizing said water to form steam, condensing water from said cooled vapors at a pressure and temperature substantially higher than is maintained in said water vaporizing zone, separating said condensed water, reducing the pressure on said water, introducing said water into said Water vaporizing zone, removing water from said Water vaporizing zone, introducing said removed water into contact with the compressed vapors at a pressure substantially higher than said water vaporizin zone, cooling said compressed vapors by contact between the vapors and the water, and condensing said compressed vapors at said. higher pressure;

5. A method for steam distillation, which comprises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature and pressure, removing vapors of said material mixed with water vapors from the unvaporized residue, compressing the mixed vapors to a pressure substantially higher than the pressure in said vaporizing zone, heating the vapors by such compression, passing the compressed vapors in heat exchange with Water in a water vaporizing zone maintained at a pressure substantially that of the distillation zone to cool the vapors and to supply latent heat of vaporiza tion of the water, condensing a portion of the compressed vapors, separating condensate from the uncondensed vapors at such higher pressure, further compressing said uncondensedvapors to a higher pressure and thus further heating said vapors by such compression, passing said further compressed vapors in heat exchange with said Water in said vaporizing zone to further supply latent heat of vaporization of said water in said vaporizing zone and. to cool the further compressedvapors, condensing water from said further compressed vapors at such higher pressure, separating such water condensate from the un-. condensed; vapors at such higher pressure, reducingthe pressure. on said water condensate, andintroducing such Water at such reducedpressure into saidwater vaporizing zone.

6 A methodifor steam distillation, which com,-

prises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature and pressure, removing vapors of said material mixed with water vapors from the unvaporized residue, compressing the mixed vs pors to a pressure substantially higher than the pressure in said vaporizing zone, heating the vapors by such compression, passing the com pressed vapors in heat exchange with water in a water vaporizin zone maintained at a pressure substantially that of the distillation zone to cool the vapors and to supply latent heat of vaporization of the water, condensing a portion of the compressed vapors, separating condensate from the uncondensed vapors at such higher pressure, further compressing said uncondensed vapors to a higher pressure and thus further heating said vapors by such compression, passing said further compressed vapors in heat exchange with said water in said vaporizing zone to further supply latent heat of vaporization of said water in said vaporizing zone and to cool the further compressed vapors, separating water from said water vaporizing zone, commingling said water with the further compressed vapors at a pressure substantially higher than the vaporizing zone, and cooling the compressed vapors at said higher pressure, condensing water from said further compressed vapors at such higher pressure, separating such 1 water condensatefrom the uncondensed vapors at such higher pressure, reducing the pressure on said water condensate, and introducing such Water at such reduced pressure into said water vaporizing zone.

'7. A method for steam distillation, which com prises passing steam into a material undergoing distillation in a distillation Zone at a distillation temperature and pressure, removing vapors of said material mixed with water vapors from the unvaporized residue, compressing the mixed vapors to a pressure substantially higher than the pressure in said vaporizing zone, heating the vapors by such compression, passing the compressed vapors in heat exchange with water; in a water vaporizing zon maintained at a pressure substantially that of the distillation zone to cool the vapors and to supply latent heat of vaporize tion of the water, condensing a portion of the compressed vapors, separating condensate from the uncondensed vapors at such higher pressure, further compressing said uncondensed vapors to a higher pressure and thus further heating said vapors by such compression, separating water from said water vaporizing zone, commingling said water with the further compressed vapors to cool the same, condensing water from said further compressed vapors at such higherpressure, separating such water condensate from the uncondensed vapors at such higher pressure, reducing the pressure on said water condensate, and introducing such water at such reduced pressure into said water vaporizing zone.

8. A, method for steam distillation, which comprises passing steam into a. material undergoing; distillation in a. distillation zone at a, distillation temperature, removing the vapors containing steam from the undistilled residue, compressing the mixed vapors above the pressure at which distillation occurred, heating said mixed vapors by such compression above the temperature of distillation, cooling said mixed vapors tocon,- dense water from said vapors at said higher pressure, reducing the pressure on said water to substantially the pressure or said distillation, vaporizing a, portion 01' said water at said lower pressure to form steam, leaving some water un vaporized, introducing said steam into said distillation zone, passing said unvaporized water in contact with said compressed vapors at a pressure substantially higher than the pressure in the vaporizing zone, and cooling said compressed vapors by direct heat exchange between said water and said compressed vapors at said higher pressure.

9. A method for steam distillation, which comprises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature, removing vapors containing steam from the undistilled residue, compressing said mixed vapors above the pressure at which distillation occurred, heating said mixed Vapors by such compression above the temperature of distillation, cooling said mixed vapors, condensing water, separating said condensed water, reducing the pressure on said water, introducing said water into a water vaporizing zone, vaporizing said water to form steam, introducing said steam into said distillation zone, removin water from said water vaporizing zone, and introducing said removed water into contact with the compressed vapors undergoing condensation at a pressure substantially higher than the pressure in said water vaporizing zone.

10. A method for steam distillation, which comprises passing steam into a material undergoing distillation in a distillation Zone at a distillation temperature, removing vapors containing steam from the undistilled residue, compressing said mixed vapors above the pressure at which distillation occurred, heating said mixed vapors by such compression above the temperature of distillation, cooling said mixed vapors, condensing water, separating said condensed water, reducing the pressure on said water, introducing said water into a water vaporizing zone, vaporizing said water to form steam in said vaporizing zone, partially condensing said steam, separating the uncondensed steam from the steam condensate, introducing the uncondensed steam vapors into said distillation zone, and commingling the steam condensate with the water in said water vaporizing zone.

11. A process of steam distillation, which comprises generating steam in a steam generation zone, introducing heated material into a distillation zone, said material being heated sufiiciently to supply heat of vaporization of said material in said distillation zone, introducing said steam into the distillation zone, removing mixed vapors containing steam from said distillation zone, compressing said vapors above the pressure of said distillation zone and said steam generation zone,

thus heating the mixed vapors by said compression, transferring a portion only of the heat of the compressed vapors to the steam passing to said vaporization zone, separately removin the remaining portion of the heat added by compression to the compressed vapors, further cooling said compressed vapors, condensing the water in said compressed mixed vapors at an elevated pressure higher than said distillation pressure, removing water of condensation, reducing the pressure on said water, and introducing said water into said steam generation zone, whereby the latent heat of vaporization of water vaporized in said steam generation zone is supplied solely by the heat added to the water by said compressed vapors.

12. A method of steam distillation, which comprises vaporizing water in a water vaporizing zone pressed vaporsby heat exchange with water undergoing vaporization in the water vaporizing zone, increasing the heat content of the water undergoing vaporization and generated steam by an amount less than the heat of compression, additionally cooling the compressed vapors, by a heat exchange in addition to said aforementioned heat exchange, and thereby removing the heat of compression and latent heat of condensation of the steam in said compressed mixed vapors and thus condensing steam at said higher pressure, removing the condensed steam, reducing th pressure on said steam condensate, and introducing said condensate into the water vaporizing zone wherein the Wateris vaporized, the latent heat of vaporization of water being supplied solely by the heat added to said Water by said compressed vapors.

13. A method for steam distillation, which comprises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature and pressure, removing vapors of said material mixed with water vapors from the unvaporized residue, compressing the mixed Vapors to a pressure substantially higher than the pressure in said vaporizing zone, heating the vapors by such compression, passing the compressed vapors in heat exchange with water in a water vaporizing zone maintained at a pressure substantially that of the distillation zone to cool the vapors and to supply latent heat of vaporization of the water, condensing a portion of the compressed vapors of the vaporized material and of the compressed water vapor, separating condensate from the uncondensed vapors at such higher pressure, further compressing said uncondensed vapors to a higher pressure and thus further heating said vapors by such compression, passing said further compressed vapors in heat exchange with said water in said vaporizing zone to further supply latent heat of vaporization of said water in said vaporizing zone and to cool the further compressed vapors, condensing water and said vaporized material from said further compressed vapors at such higher pressure, separating such water condensate from the uncondensed vapors at such higher pressure, reducing the pressure on said water condensate, and introducing such water at such reduced pressure into said water vaporizing zone.

14., A method for steam distillation, which comprises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature and pressure, removing vapors of said material mixed with water vapors from the unvaporized residue, compressin the mixed vapors to a pressure substantially higher than the pressure insaid vaporizing zone, heating the vapors by such compression, passing the compressed vapors in heat exchange with water in a water vaporizing zone maintained at a pressure substantially that of the distillation zone to cool the vapors and to supply latent heat of vaporization of the water, condensin a portion or the compressed vapors of the vaporized material and of the compressed water vapor, separating condensate from the uncondehsed vapors at such higher pressure, further compressing said uncondensed vapors to a higher pressure and thus further heating said vapors by such compression, passing said further compressed vapors in heat exchange with said water in said vaporizing zone to further supply latent heat of vaporization of said water in said vaporizing zone and to cool the further compressed vapors, separating water from said water va'porizi'n'g zone, oorn'mlnglihg said water with the further compressed vapors at a pressure substantially higher than the vaporizing zone and cooling said vapors at said higher pressure, condensing Water and said vaporized material from said further compressed vapors at such higher pressure, separating sil'ch water condensate from the uncondensed Vapors at such higher pressure, reducing the pressure on said Water condensate, and introducing such water such reduced pressure into said water vaporizing zone.

15. A method for steam distillation, which com prises passing steam into a material undergoing distillation in a distillation zone at a distillation temperature and pressure, removing vapors of said material mixed with water vapors from the unvaporized residue, compressing the mixedvapass to a pressure substautiany higher than the pressure in said vaporizingzo'ne, heating the vapors by such cempression, passing the oompressed vapors heat exchange with water in a water vaporizing zone maintained at a pressure 1 substantially that or the distillation cone to cool the vapors to supply latent heat of vaporization of the water, condensing a portion of the c'e'lhpressed vapors or the "vaporized material and of the compressed water vapor, separating condeiisate from the tihoo'ndeh'sed vapors at such higher pressure, rur t'her com ressing sa'i'd unconden'se'd vapors to a higher pressure and thus further heating isa id vapors lay such compression, separating wa ter from said Waiter vaporizing Zone, coi nlilliiglilig said Water with the further com-pressed vapors to cool the saline, oon darising wa ter and Said vaporized material from said fur th'er compressed vapors at such higher pressure,

separating such water condensate from the uncondensed vapors "a't si-ich higher pressure,reducing the pressure ou said water condensate, and introducing such Water at such reduced pressure lift?) Said "water vaporizing Zone.

1'6. A process or steam distillation, which conrprises passing steamt'hrough a material undergo-- 'ing (llistllla' t iol'l in a distillation zone heating Said material suffic'ientls' to sup ly the heat of vaporization of said material, removing "mixed vapors of water and the vaporized *material from said distillation zone, compressin the nriX'ed vapors to a pressure substantially higher than the dis- 'tllla tion pressure thus heating'the mixed vapors to a temperature substantially higher than the distillation temperature, passing said compressed vapors in heat exchange with Water and thus heating said \i'z'aiterto a tem erature 'su'fil- 'cient to vaporize said water at a. pressure substantially lower than the pressure of said compressed vapors but below the boiling point of the water at the pressure of the compressed vapors in heat exchange with the water, vaporizing the heated water at a pressure substantially lower than the said pressure of said compressed vapors the l'at'rll; neat of vaporiaation "of Water having been added solely by said heat exchange with the compressed vapors, introducing the resultant steam into the still, cooling the compressed vapors separately and independently from the aforesaid heat exchange between said water and the compressed vapors, condensing vapors of said material vaporized by said distillation in a condensation zone at a pressure substantially higher than said distillation pressure, and removing condensate from said condensation zone.

ii. A process of steam distillation, which comprises passing steam through a material undergoin'g distillation in a distillation zone, heating said material suliici'ently to supply the heat of vaporization of said material, removing mixed vapors of steam and vaporized material from the distillation zone, compressing the mixed vapors to a pressure substantially higher than the distillation pressure, condensing water at said higher pressure, separating the condensed water from uncondensed vaporous material, heating said Water by heat exchange with said compressed gases to partially cool said compressed gases, vaporizing said heated Water in a vaporizing zone at a vaporizing pressure substantially lower than the pressure or said uncondensed vaporous material the latent heat of vaporization of water having been added solely by the heat exchange with said compressed vapors, introducing the resultant steam into the distillation zone, and further and separately cooling the uncondensed vaporous material at a pressure substantially higher than the vaporizing pressure or the water in said vaporizing zone.

18. A process of steam distillation, which oomprises passing steam through a material undergoing distillation in a distillation zone at a distillation temperature and pressure, removing mixed vapors of steam and vaporized material from the distillation :zone, compressing the mixed vapors to a pressure substantially higher than the distillation pressure and thus heating the com- -pressed gases to atemperaturesubstantially higher than the distillation pressure, partially heat exchanging said compressed vapors with relatively cool Water and partially condensing said vapors to form a water condensate in a condensation zone, separately removing the water from the condensed compressed vapors, reducing the pressure on said water condensate and vaporizing steam and thus cooling the water "to a temperature substantially :below "the temperature of condensation of said water, passing such relatively .cool Wat-er in said heat exchange with said oompressed vapors, further and separately'cooling the uncondensed compressed vapors in -a separate condensation zone at a pressure substantially higher than the pressure the vaporization zone to condense distilled material, and removing the condensate from the material from said higher pressure condensation zone.

RONAIZD W. HEATH.

:References Cited in the rfile of this patent UNITED STATES PATENTS Number Name Date s49go79 Siebe'l Apr. "9, 1907 1,200,996 "soder lund 10st. I0,'191'6 1-,425g005 Gienuolre Au'g. 8, 1922 1,439,009 Rohmer et al. Apr. 1, 1924 1g8 22,'-'45 5 'Ric'ard --'et al. -Bept. '8, 1931 213272643 Houghland 'lAug. 24, "1948 

11. A PROCESS OF STEAM DISTILLATION, WHICH COMPRISES GENERATING STEAM IN A STEAM GENERATION ZONE, INTRODUCING HEATED MATERIAL INTO A DISTILLATION ZONE, SAID MATERIAL BEING HEATED SUFFICIENTLY TO SUPPLY HEAT OF VAPORIZATION OF SAID MATERIAL IN SAID DISTILLATION ZONE, INTRODUCING SAID STEAM INTO THE DISTILLATION ZONE, REMOVING MIXED VAPORS CONTAINING STEAM FROM SAID DISTILLATION ZONE, COMPRESSING SAID VAPORS ABOVE THE PRESSURE OF SAID DISTILLATION ZONE AND SAID STEAM GENERATION ZONE, THUS HEATING THE MIXED VAPORS BY SAID COMPRESSION, TRANSFERRING A PORTION ONLY OF THE HEAT OF THE COMPRESSED VAPORS TO THE STEAM PASSING TO SAID VAPORIZATION ZONE, SEPARATELY REMOVING THE REMAINING PORTION OF THE HEAT ADDED BY COMPRESSION TO THE COMPRESSED VAPORS, FURTHER COOLING SAID COMPRESSED VAPORS, CONDENSING THE WATER IN SAID COMPRESSED MIXED VAPORS AT AN ELEVATED PRESSURE HIGHER THAN SAID DISTILLATION PRESSURE, REMOVING WATER OF CONDENSATION, REDUCING THE PRESSURE ON SAID WATER, AND INTRODUCING SAID WATER INTO SAID STEAM GENERATION ZONE, WHEREBY THE LATENT HEAT OF VAPORIZATION OF WATER VAPORIZED IN SAID STEAM GENERATION ZONE IS SUPPLIED SOLELY BY THE HEAT ADDED TO THE WATER BY SAID COMPRESSED VAPORS. 